This also affects gnome fallback. What is odd is that I made two installs. First a temporary test install, and I didn't get this bug. Second, on the proper install, I did. Perhaps it is because I never ran firefox under Unity on the first install.
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Alistair BuxtonNov 9 '12 at 2:20

I can't reproduce this with a clean firefox profile so I'm guessing webapps preview did something bad to my old profile that I copied over from 12.04
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Alistair BuxtonNov 9 '12 at 2:29